Improve console log message for CORS failure

Source/core/loader/DocumentThreadableLoader.cpp

Index: Source/core/loader/DocumentThreadableLoader.cpp
diff --git a/Source/core/loader/DocumentThreadableLoader.cpp b/Source/core/loader/DocumentThreadableLoader.cpp
index f33cff26d4e913122b92fac461e3dc600d073463..6f9d12c98a04819ff87a5808cfe4d59b2f3be406 100644
--- a/Source/core/loader/DocumentThreadableLoader.cpp
+++ b/Source/core/loader/DocumentThreadableLoader.cpp
@@ -299,12 +299,17 @@ void DocumentThreadableLoader::redirectReceived(Resource* resource, ResourceRequ
         // Non-simple cross origin requests (both preflight and actual one) are
         // not allowed to follow redirect.
         if (m_crossOriginNonSimpleRequest) {
-            accessControlErrorDescription = "The request was redirected to '"+ request.url().string() + "', which is disallowed for cross-origin requests that require preflight.";
+            accessControlErrorDescription = "The request was redirected to '" + request.url().string() + "', which is disallowed for cross-origin requests that require preflight.";
         } else {
             // The redirect response must pass the access control check if the
             // original request was not same-origin.
-            allowRedirect = CrossOriginAccessControl::isLegalRedirectLocation(request.url(), accessControlErrorDescription)
-                && (m_sameOriginRequest || passesAccessControlCheck(redirectResponse, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription));
+            if (CrossOriginAccessControl::isLegalRedirectLocation(request.url(), accessControlErrorDescription)) {
+                if (m_sameOriginRequest || passesAccessControlCheck(redirectResponse, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription)) {
+                    allowRedirect = true;
+                } else {
+                    accessControlErrorDescription = "The request was redirected to '" + request.url().string() + "', and has been blocked from loading by Cross-Origin Resource Sharing policy: " + accessControlErrorDescription;
+                }
+            }
         }
 
         if (allowRedirect) {
@@ -394,7 +399,7 @@ void DocumentThreadableLoader::handlePreflightResponse(const ResourceResponse& r
     String accessControlErrorDescription;
 
     if (!passesAccessControlCheck(response, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription)) {
-        handlePreflightFailure(response.url().string(), accessControlErrorDescription);
+        handlePreflightFailure(response.url().string(), "Response for preflight doesn't pass the access control check: " + accessControlErrorDescription);
         return;
     }
 
@@ -458,7 +463,7 @@ void DocumentThreadableLoader::handleResponse(unsigned long identifier, const Re
         String accessControlErrorDescription;
         if (!passesAccessControlCheck(response, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription)) {
             reportResponseReceived(identifier, response);
-            m_client->didFailAccessControlCheck(ResourceError(errorDomainBlinkInternal, 0, response.url().string(), accessControlErrorDescription));
+            m_client->didFailAccessControlCheck(ResourceError(errorDomainBlinkInternal, 0, response.url().string(), "Received response but it doesn't pass the access control check: " + accessControlErrorDescription));

[sof, 2015/06/25 11:24:18]

The prefixed text strikes me as redundant (and long) -- the error message makes
it implicitly clear that a response was received.

[tyoshino (SeeGerritForStatus), 2016/07/22 12:46:45]

OK. Removed

             return;
         }
     }